Tolong bantu yang no 3 sampai nomor 6​

Jawaban:

3. -3r² – 7r² +9r² = -r²

4. (3x + 4x) (-5y + 7y) = 7x + 2y

5. 4y + 7z -3y – 5z = y + 2z

6. (5x – x ) + ( -7y – (-3y) ) + ( 3z – (-5z) )

4x – 4y + 8z